Alpha-blocking drugs toxicity

D. Toxicity and Interactions Sedation is common, especially with diphenhydramine, doxylamine, and promethazine. It is much less common with second-generation agents, which do not enter the CNS readily. Antimuscarinic effects such as dry mouth and blurred vision occur with some first-generation drugs in some patients. Alpha-blocking actions may cause orthostatic hypotension. 

Thymoxamine, a selective alpha adrenergic blocking drug, is non-toxic and non-irritating in a 0.5% solution when used in a 5% solution it may produce paralytic ptosis and chemosis. 

Microtubules The microtubules of the cytoskeleton and mitotic spindle consist of tubulin polymers. These tubulins are heterogeneous among species. Structural features of alpha-tubulins in helminths may account for the selective toxicity of benzimidazole drugs (eg, mebendazole). These agents bind to microtubules in helminths to block transport processes. 

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